1. Field of the Invention
The present invention relates to a preheating apparatus which is utilized in measuring devices such as a test handler which measures the performance of semiconductor device at a high temperature and more particularly, to a semiconductor device preheating apparatus which has an excellent uniform heating capability and is easy in manufacture and control.
2. Description of the Prior Art
Various types of the preheating apparatuses for use in a test handler are well known in the art. One conventional preheating apparatus is illustrated in FIGS. 1 and 2. As shown in FIGS. 1 and 2, the conventional preheating apparatus comprises a hot tray 41, a heater 40 attached at the rear surface of the hot tray 41, a plurality of partitions 42 fixed in front of the hot tray 41 at a predetermined interval for forming a plurality of heating chambers 41a containing and heating semiconductor devices 43 therein, and a stop bar 45 provided at the lower side of the hot tray 41 for blocking the semiconductor devices 43 which are dropped down from respective heating chambers 41a.
In addition, a motor 41 is mounted at one side of the hot tray 41 and a pair of drive sprockets 46 are mounted at a shaft 45' of the motor 41. The drive sprockets 46 are connected to a pair of driven sprockets (not shown) by means of a pair of chains 47.
Also, a plurality of cleat members 48 are attached to the chains 47 so that they may be conveyed together with the chains 47. And, a number of solenoids 49 are mounted at the lower side of respective heating chambers 41a so that their plunger rods 49a penetrate each passage of the heating chambers 41a. That is, the passage of the respective heating chambers 41a is opened or closed by the respective plunger rod 49a of the solenoid 49. In FIG. 2, reference numeral 50 is a cover plate of the apparatus.
In such a conventional apparatus, when semiconductor devices 43 are supplied consecutively through the upper portion of each of the heating chambers 41a of the hot tray 41, the semiconductor devices 43 are stored in the heating chambers 41a by the plunger rods 49a of the solenoid 49 and preheated by heat from the heater 40. After a predetermined time has elapsed, the heating chambers 41a are opened in turn by the operation of the solenoids 49 so that the semiconductor devices 43 are held by the stop bar 44. In this state, the cleats 48 are moved toward the outlet 51 by the driving force from the motor 45 so that the semiconductor devices 43 which have been laid on the stop bar 44 are conveyed by the cleats 48 and dropped down in turn through the outlet 51.
Such a conventional apparatus, however, has disadvantages in that since the construction is relatively complicated it is improper for a small-sized measuring device and expensive in manufacturing cost. Also, since it has a number of inlets for inserting semiconductor devices into the heating chambers, it is difficult to apply the apparatus to automatic system.